Fuel systems on board vehicles of various types generally comprise devices for the ventilation of hydrocarbons contained in the tank. They may also include devices for supplying the engine with fuel. Such devices form the link between elements contained in the tank (valves, fuel pump, etc.) and elements positioned outside the tank (canister, fill pipe, etc.). Penetration through the wall of the tank must take into account the low permeability requirements laid down by current environmental standards (LEV II and PZEV for example). For this purpose, the reduction in the number and size of the openings in the wall of the tank constitutes a favourable factor in reducing evaporative losses. However, this makes it more difficult to insert components into the tank and position them therein.
Application EP 1110697 in the name of the Applicant discloses a process for moulding a fuel tank using a parison in several sections so as to be able to insert accessories into the tank at the same time as it is moulded. For this purpose, a tubular parison is extruded, then, on exiting the die, two longitudinal cuts are made in it, along two opposing generatrices, before being converted into two separate sheets by transverse cutting of the split parison. Application EP '697 does not describe how the sheets are held after the cuts have been made or how the longitudinal cuts are made over the entire length of the parison.
One process for manufacturing a hollow body by moulding, starting from an extruded parison, is also described in Application US 2006/0001197. During this process a tubular stream of molten plastic is extruded and positioned between the parts of a mould that define a mould cavity for the stream of material, then it is taken up by a tensioning device so that the stream of material is extended transversely with respect to the extrusion direction and beyond the lateral edges the mould cavity. The mould is then closed and a hollow body is moulded. When the mould is closed, excrescences are created in the stream of material and outside the lateral edges of the mould cavity. These are then cut longitudinally on each side of the mould along edges that extend in the extrusion direction so as to be able to release the tensioning device. The longitudinal cuts are not made over the entire length of the excrescences so that the moulded hollow body has a free uncut edge. The device and process described in Application US '197 are therefore not suitable for cutting a parison so as to form two separate sheets as in Application EP '697.